1. Field of the Invention
The present invention relates to winches for watercraft, particularly sailboats. The invention has particular, but not exclusive, applicability to winches that are powered by a motor and capable of being wound by operation of the motor in the forwards direction and in the reverse direction.
2. Related Art
Winches are well known for use in manoeuvring the sails on a sailboat by controlling the tension on the boat's running and rigging lines. These lines for example may be sail sheets and sail halyards, which are referred to collectively in this disclosure as “ropes”. Each rope can be considered to have a loaded end (connected to a sail) and an unloaded end (the “tail” of the rope, which may be collected in a cockpit of the boat).
A typical winch includes a rotatable drum mounted with respect to a deck of the boat. The loaded end of the rope is drawn onto the drum by rotation of the drum. Hauling the loaded end of the rope onto the drum in this way is referred to in this disclosure as “forward winding” of the winch. This rotation is typically clockwise rotation, although this is not essential. Rotation of the drum may be achieved by hand-cranking of the winch using a winch handle inserted into a drive socket at the upper end of the winch. Additionally or alternatively, the winch may be rotated by operation of an electric or hydraulic motor. Reduction gearing is provided in order to improve mechanical advantage and allow the rope to be drawn onto the drum even under heavy loads. Particularly for hand-cranking operation of the winch, there may be provided at least two (and sometimes three or four) reduction gear ratios. In the case of two gear ratios, the relevant gear is typically selected simply by the user driving the winch handle in either the clockwise or anticlockwise direction.
There are typically three or four turns of rope held on the winch drum. The diameter of the winch drum typically enlarges slightly from the axial lower end of the drum towards the axial upper end of the drum. This encourages the loaded end of the rope to be located at the axial lower end of the drum. The three or four turns of rope on the drum typically provide a great deal of frictional hold on the rope. The unloaded end of the rope may therefore be simply held in a cleat in order to retain the rope on the winch and retain the load on the loaded end of the rope. However, it is common to incorporate a cleat onto the winch in the form of a self-tailing arrangement, described in more detail below.
The self-tailing arrangement is typically located at the upper end of the winch. The self-tailing arrangement has a pair of opposed rope lock rings with optional gripping features. The rope lock rings are typically spring biased towards each other to allow a range of rope diameters to fit into the channel defined between the rope lock rings and be gripped by the rope lock rings. The rope lock rings rotate with the drum. A feeder arm is provided in order to guide rope from the upper end of the drum into the channel between the rope lock rings. The feeder arm is fixed with respect to the winch, so that the feeder arm does not rotate with the winch drum or the rope lock rings. The rope then passes along the channel between the rope lock rings for nearly a full turn around the winch, the rope exiting the channel at an unloaded end of the rope adjacent the feeder arm, optionally guided out of the channel between the rope lock rings by a suitable guide feature typically known as a stripper. Forward winding of the winch therefore draws loaded rope onto the lower end of the drum, thereby reducing the length of rope that is loaded between the winch and the sail. An amount of rope corresponding to the amount drawn onto the winch drum is guided into the self-tailing unit by the feeder arm. A corresponding amount of rope is paid out the self-tailing unit via the stripper and into, e.g. the cockpit of the boat, thereby to increase the length of rope that is unloaded. The rope is gripped (cleated) in the self-tailing arrangement by the rope lock rings.
As well as hauling rope in, it is also required to pay rope out from the winch, in order to manoeuvre the sails to an optimum position as determined by the skipper of the boat. With self-tailing winches of the type described above, rope is typically paid out manually. The operator takes the unloaded rope adjacent the self tailing arrangement and pulls the rope radially out of the channel defined by the rope lock rings. The operator applies some tension to the rope in order to replace the gripping force provided by the self-tailing arrangement. The operator may let off one or two turns of rope from the winch drum. The operator must then carefully pay out the rope, to allow it to slide around the remaining turns on the winch drum. As will be understood, this operation is potentially hazardous, given the high loads experienced by the ropes on typical sailboats. There is risk of injury to the operator, risk of damage to the sailboat and a likelihood of (at least temporary) loss of control of at least some aspect of the sailboat if the rope is accidentally let out in an uncontrolled manner.
It is known to address this problem using a winch which is capable of powered reverse winding. In the present disclosure, “reverse winding” relates to controlled rotation of the winch drum in the opposite direction to forward winding, reverse winding thereby increasing the length of loaded rope and decreasing the length of unloaded rope. However, providing a winch with powered reverse winding capability is relatively complex since typically the additional capability of the winch must not compromise the primary function of the winch to haul in loaded rope as efficiently as possible.
There are known powered reverse winding winches. GB-A-2276137 discloses a powered winch which has an electric motor capable of driving the winch in the forward direction with different gear ratios. Reverse winding of the winch is made possible by the inclusion of a sun and planetary gear mechanism controlled by the motor. This arrangement is complex and would be difficult to manufacture and assemble.
Operation of electrically powered winches is typically carried out by activation of suitable switches in order to supply power to the electric motor. For some known powered winches, it is necessary to provide several controls, in order to for the user to select the gear ratio to be used by the winch and in order for the user to activate power to the winch. For example, a control (which may be mechanical or electrical) may be provided in order to select one of a several modes of operation e.g. “forward wind only, different speeds” or “forward/reverse wind”. One or more further controls (typically one or more switches) must then be activated in order to deliver power to the electric motor, allowing the user to select, for example “fast forward wind”, “slow forward wind” or “reverse wind”, but only after operation and/or inspection of at least two controls. Such a non-intuitive control system can be difficult for the user to operate in challenging sailing conditions.
Another known winch is disclosed in WO2011/005172. The winch is disclosed as being capable of powered forward winding and powered reverse winding, however it is not explained in WO2011/005172 how gearing may be arranged in the winch in order to allow powered reverse winding. WO2011/005172 discloses a self-tailing arrangement having an upper rope lock ring and a lower rope lock ring, both lock rings being rotatable with the winch drum. The lower rope lock ring is held in a fixed axial position (but is rotatable as previously mentioned) and the upper rope lock ring is skew spring-mounted. During rotation of the winch drum, the upper rope lock ring is subjected to a dynamic asymmetric motion pattern so that the channel between the rope lock rings is at its widest adjacent the self-tailing arm and at its narrowest diametrically opposite the self-tailing arm. This dynamic asymmetric motion pattern is provided by a forcing means inserted into the channel between the rope lock rings forcing the rope lock rings apart against the force of the springs acting on the upper rope lock ring. The rope lock rings additionally have a bulge of uniform height formed around the self-tailing arrangement. The effect of this, combined with the motion pattern of the rope lock rings, is that the rope is firmly held in the channel between the rope lock rings at the position diametrically opposite the self-tailing arm, and yet the rope can be fed into and fed out of the self-tailing arrangement, past the bulge, at a position adjacent the self-tailing arm due to the forcing-open of the rope lock rings. This is stated to allow the unloaded rope to be more easily and automatically fed into the self-tailing arrangement during reverse winding.